1. Field of Invention
This invention relates generally to the ultrasonic welding of Velcro tape components to a fabric, and more particularly to a motorless Velcro tape feed and cut assembly which acts as a slave unit with respect to an ultrasonic welding machine and cooperates with the reciprocating horn thereof, whereby the up and down movement of the horn causes the assembly to feed the leading end of a Velcro tape into an anvil channel and to sever this end from the tape to form a Velcro component that is then welded to a fabric.
2. The Prior Art
It is known to use in place of buttons, zippers and other conventional types of fasteners, releasable "Velcro" fasteners which serve to hold together fabric panels or other complementary pieces. A Velcro fastener is constituted by a male or hook component created by a uniform array of stiff hooks and a female or loop component whose surface is constituted by a pile of tiny soft loops. When the male and female components are pressed together, the hooks become embedded in the loops and are held thereby until the components are peeled apart.
Velcro fasteners are snug, jam proof and washable. The components thereof are available in tape form which can be cut to a desired size. The male hook component, usually fabricated of nylon, is woven in the form of raised loops which are heated to retain their shape, the loops being then clipped to form the desired hooks. The loop or female component is also fabricated of nylon, use being made of a ground tape interwoven with a dense multiplicity of yarns to form a pile surface that is then napped to create a continuous mass of uncut loops designed to couple with the male hooks.
As disclosed in my prior U.S. Pat. No. 4,382,303, it is known to produce garments whose closures are constituted by Velcro fastener components that are ultrasonically welded to fabric panels. Ultrasonic welding may be used to weld together two or more pieces or sheets of thermoplastic material. This is accomplished by interposing the sheets between a "sonotrode" horn and an anvil. The horn is excited into vibration at an ultrasonic frequency and the ultrasonic energy is tranformed into heat which softens the thermoplastic sheets and causes them to fuse together. The amount of heat generated is controlled by the adjustable amplitude of ultrasonic vibration.
While machines are known capable of dispensing or die cutting pieces of Velcro tape in a predetermined size appropriate to a fastener for a particular fabric application, it has not heretofore been possible to automate the ultrasonic welding operation. Thus, in a typical welding operation such as that necessary to produce Velcro fasteners for garments of the type disclosed in my above-identified patent, an operator must manually place a Velcro component over a sheet of fabric material at an appropriate position thereon, and then operate an ultrasonic welding machine to weld the component to the sheet.
This hand operation is time consuming and subject to human error, as a consequence of which the cost of producing garments having Velcro fasteners is relatively high. Where the garments are intended to be of the disposable type and make use of inexpensive non-woven fabrics, the costs incurred by conventional ultrasonic welding operations for the Velcro fasteners raises the production cost of the garment to a level approaching a point that is not acceptable in disposables.